Ventilators can be employed to evacuate air and other gases from enclosed spaces. Such enclosed spaces can include the roof space or interior of commercial and domestic buildings, shipping containers, portable buildings and sheds, automobiles etc. The air and other gases evacuated can include warm or heated gases, moist gases, gas containing contaminants such as contaminated air or toxic fumes, stale gases (especially air) etc.
A ventilator known as a rotor ventilator comprises a rotor having a plurality of vanes which are oriented in use to capture ambient wind to drive (rotate) the ventilator rotor. In use, when the ventilator rotor is wind driven, air adjacent to the vanes is forced outwardly by the rotating vanes, and this air is in turn replaced by air from the enclosed space. This causes, in effect, a pumping out of air from the space.